The move sets down a marker for when the race for this Democrat-held seat, a top target of national Republicans, will begin to heat up. The buy begins Sept. 15 and runs through Election Day on both cable and broadcast in the 52nd District, located in and around San Diego.

DeMaio is a top Republican recruit facing vulnerable freshman Rep. Scott Peters, who defeated a GOP incumbent by a slim margin in 2012. The district is one of the most expensive in the country to air TV ads, and Peters' race last cycle was among the priciest .

Peters has yet to reserve fall television airtime, but he should have ample funds to do so.

The incumbent raised more than DeMaio in the second quarter, bringing in $702,000 to DeMaio's $600,000 , and had more in the bank. As of June 30, Peters had $1.9 million in cash on hand to DeMaio's $1.5 million.

The Democratic Congressional Campaign Committee and the National Republican Congressional Committee have also reserved airtime here in the fall. The DCCC reserved $1.4 million , while the NRCC reserved $1.7 million .

With outside group spending factored in, this contest will likely once again be one of the most expensive House races of the cycle.

California's 52nd District is rated a Tossup by the Rothenberg Political Report/Roll Call.